Switching mechanism



March 1, 1966 Filed. March 12, 1964 J. L, HARRIS SWITCHING MECHANISM 2Sheets-Sheet l I NVEN TOR.

United States Patent 3,238,328 SWITCHING MECHANISM John L. Harris,Whitefish Bay, Wis., assiguor to Miller- Harris Instruments Company,Milwaukee, Wis, a corporation of Wisconsin Filed Mar. 12, 1964, Ser. No.351,402 14 Claims. (Cl. 2110-97) This invention relates to switchingmechanism.

The object of the invention is to provide a switch operating mechanismproviding high capacity switching with a minimum of operating forcerequired. This is accomplished in part by balancing the positive springrate of one spring with a negative spring rate of an opposing spring.The invention also includes the provision of a flywheel which controlsthe make and break Speeds and provides extra operating force at thepoint of opening the contacts.

Other objects will appear as this description proceeds.

For a full disclosure of the invention reference is made to thefollowing detailed description and to the accompanying drawings inwhich:

FIG. 1 is a front view with the cover removed of a time controlmechanism embodying the invention;

FIG. 2 is a side sectional view taken on line 22 of FIG. 1;

FIG. 3 is a sectional view of the flywheel construction;

FIG. 4 is a view similar to FIG. 1 showing the parts in anotherposition;

FIG. 5 is a similar view to FIG. 4 showing the parts after returnmovement;

FIG. 6 is a sectional view taken on line 66 of FIG. 1;

FIG. 7 is a side view of the invention applied to an electromagneticswitch; and

FIG. 8 is a rear view of FIG. 7 taken on line 88 of FIG. 7.

Referring to FIG. 1, the invention is shown applied to a time controlmechanism of the type shown in my copending application, Serial No.262,471, filed March 4, 1963.

This time control mechanism includes a base bracket 1 which is ofbox-like configuration and carries a switch panel 2. This switch panelis formed with gears 3 which extend into suitable slots in theout-turned top section 4 of the base member. The lower end of the switchpanel 2 fits over studs, 5, 6 and 7 which are staked into the baseplate 1. An offset front bracket 8 mounts over the switch panel 2 and isheld in place by screws 9' which are threaded into the studs 5 and 7.

The switch panel 2 carries suitable switch mechanism. In the embodimentillustrated there are two separate switches. One includes a switch blade10 which is attached to a bracket 11 carried by the panel. This switchblade 10 extends between contact brackets 12 and 13. This mechanism thusforms a double throw switch. The second switch includes a switch blade14 which is carried by a bracket 15 attached to the panel. This switchblade carries a contact 16 which cooperates with a stationary contactcarried by a contact bracket 17 mounted on the panel 2.

The switch blade 10 is biased to the right tending to engage with thecontact carried by the contact bracket 13. The switch blade 14 is alsobiased to the right tending to engage with the stationary contactcarried by contact bracket 17. These switch blades are operated by studs20 and 21 which are carried by a sliding switch blade operator 22. Thisswitch blade operator 22 is formed of phenolic material and is providedwith slots fitting over studs 6 and 7 carried by the base plate 1. Thestuds 6 and 7 are formed with shoulders 23 which maintain switch bladeoperator 22 in position against the base member 1.

Mounted on studs 5 and 7 and in front of the switch blade operator 22,is a sliding cam follower member 25. As shown in FIG. 2 the member 25fits between the shoulder 23 of the studs 5 and 7 and the switch panel2. Both the switch blade operator 22 and the sliding cam follower 25 arefree to slide over studs 5 and 7 which serve as guides.

The cam follower member 25 is provided with a stud 30 which extends bothforwardly and rearwardly from member 25. The forward portion of stud 30carries a tension spring 31 which extends to the right and is anchoredto a stud 30 carried by the base member 1. The rear section of the stud30 serves as a bearing for a latch member 32.

This latch member 32 is arranged to engage either an in wardly extendingprojection 34 on the base member or a projection 35 forming part of theswitch operator 22. This latch member 32 is biased in a counterclockwisedirection by a suitable spring not shown.

As shown in FIG. 6, the switch operator 22 is provided with a stud 36which extends forwardly through a slot 37 (FIG. 1) in the cam followermember 25. This stud 36 carries a roller 38 which rides on a cam surface39 of a pivoted cam member 40. This member 40 is carried by a bearing 41which fits over a stud 42 extending between the front plate 8 and thebase 1. A suitable spacer 43 is provided between the cam member 40 andthe base member 1 for maintaining the cam member in proper location. Atorsion spring 45 is fitted over the bearing 41. One leg of the spring45 bears against a stud 46 carried by the front plate 8. The other legof the spring bears against a stud 47 carried by the cam member 40. Thespring 45 thus biases the cam member 40 in a counterclockwise directionabout its pivot 42 as seen in FIG. 1. The cam member 40 is formed withgear teeth 49 which mesh with teeth of a pinion 50 which form part of aflywheel 51. As shown in FIG. 3 this flywheel is formed of two flywheelportions 52 and 53 which are crossed over shoulders of the pinion 50.The pinion also serves as a bearing over a stud 54 which extends betweenthe front plate 8 and the base member 1.

As described in detail in my co-pending application, the cam followermember 25 and the latch member 32 are operated by a cam shaft assemblygenerally indicated as 55. This cam shaft assembly includes a startingcam 56 carrying a pin 57 which is adapted to engage the lower surface 58of the latch member 32. The cam shaft assembly also includes an off cam60 which is also adapted to engage the surface 58 and the latch member.The cam shaft assembly also includes a reset cam 61 which engages thecam follower member 25 for camming it to the left to starting position.This cam shaft assembly 55 is driven in a counterclockwise direction bya suitable backward mechanism. The starting cam 56 is ridden by astarting cam follower 62 which is pivoted to the base member 1 andbiased toward the cam by a torsion type spring 63.

Operation FIG. 1 shows the parts ready to begin a timing cycle. At thistime the cam follower member has been cammed to the left by the resetcam 61 bearing against a cam follower surface 65 on the member 25. Thisreset cam 61 has already cammed the follower member 25 to the leftsufliciently for the latch member 32 to get behind and engage with theprojection 34 on the base member 1. This movement to the left hasstretched the spring 31 which is biasing the came follower member 25 tothe right. At this time the camming surface 39 of the member 40 isurging the roller 38 carried by the switch operator 22 to the left. Thestuds 20 and 21 carried by the switch operator 22 are thus urging theswitch blades 10 and 14 to the left.

As the cam assembly 55 rotates counterclockwise the starting pin 57carried by starting cam 56 bears against the lower edge 58 of the latchmember 32. This causes clockwise rotation of the latch member 32 aboutits pivot 30 thus disengaging the lug 34 on the base member 1. Thespring 31 now pulls the member 22 to the right. The latch member 32 nowengages the lug 35 on the switch operator as shown in FIG. 4. Thismovement of the sliding member 25 to the right thus causes movement ofthe switch operator to the right. This permits corresponding movement ofthe switch blades 18 and 14.

When the switch operator 22 is pulled to the right by the spring 31 theroller 38 bears against the cammed surface 39 and causes clockwiserotation of the cam member 40 about its pivot 41. This same movementalso causes counterclockwise rotation of the flywheel 51 about itsbearing 54. As stated above, the surface 39 of cam member 40 is acamming surface. The configuration of this surface is plotted so thatthe angular motion of the cam member 40 progressively decreases as theswitch operator 22 moves to the right. The affect of this cammingsurface is to characterize the spring rate of the spring 45 tocompensate for the loss of tension on the spring 31 as it contracts orbecomes unstressed. It will be apparent that as the spring 31 pulls theassembly to the right the force which is available from this springreduces. This decrease in force is compensated for by the camming actionof cam surface 39 which decreases the biasing affect of the spring 45even though the actual tension of this spring is being increased.

The parts now assume the positions shown in FIG. 4. At this time theswitch blades and 14 have moved for closing the right hand contacts.Also, the switch operator 22 has moved beyond this point to an overtravel position at which spacers exist between the switch blade and theoperating studs 21 and 22.

During this motion the gear teeth 49 on the cam member cause rotation ofthe flywheel 51. The inertia of this flywheel slowed up the right handmotion of the mechanism for causing the switches to close slowly andpositively without any contact bounce.

The next step in the cycle is the tripping of the latch 32 by means ofthe off cam 60 of the cam shaft assembly. This causes the latch 32 todisengage the surface 35 of the switch operator 22. The parts now assumethe positions shown in FIG. 5.

When the latch 32 disengaged the switch operator, the caming surface 39bearing on roller 38 urged the switch operator 22 to the left. Thismotion was initially retarded by the inertia affect of the flywheel 51.The switch operator first moved to the left taking up the over traveldistance between the studs 21 and 22 and the switch blades 10 and 14. Atthe time of engagement with the switch blades the switch operator 22 wasstill moving slowly due to the inertia retarding affect of the flywheel51. However, it was also moving with a positive driving action also dueto this inertia. This caused the contacts to break slowly .andpositively for breaking the circuit with a minimum amount of arcing.

Also during this motion, the biasing affect of the spring 45 was beingincreased due to the change in leverage provided by the cam surface 39.In this reverse action the linear motion of the switch operator 22progressively decreased as the cam 40 rotated about its pivot. Thiscamming action served in effect to reverse the spring rate of the spring45 and caused the tension on the switch operator 22 to actually increaseeven though the actual tension on this spring was decreasing. Thisaffect compensates for the build up in tension on the spring switchblades 10 and 14 as they are moved against their bias.

From the foregoing description it will be apparent that the reversespring rate affect provided by the cammed surface 39 on roller 38reduces the tension required by the spring 31 when the switches areoperated on movement to the right as seen in FIG.1. This same reversalof the spring rate also reduces the tension required on spring 45 inmoving the switch blades 10 and 14 to the left on the reverse stroke.This balancing of an increasing spring rate with a decreasing springrate thus reduces the amount of energy required to operate the switchesand makes it possible to operate high capacity switches with relativelysmall operating forces. This balancing of positive and negative springrates with the inertia affect of the flywheel gives controlled speed onthe make and break of the contacts and further increases the capacity ofthe switches without requiring any additional power to operate them.

FIGURES 7 and 8 Referring to FIGS. 7 and 8, the invention is shownapplied to an electromagnetic operated switch.

As shown in FIG. 7, a switch panel 70 is supported on a box like basemember 71. This switch panel is shown as carrying a lower switchcomprising a switch blade 72 which is carried by a terminal bracket 73.This switch blade 72 carries a contact 74 which cooperates with acorresponding stationary contact carried by a contact bracket 75 alsoattached to the switch panel 70. The switch panel 70 also may carry anupper switch generally indicated as 76 of the same construction as thelower switch just described.

The box like base member 71 carrying the panel 70 is formed withopenings 77 and 78 which gives clearance for the upper and lowerswitches.

The base member 71 is mounted in a U-shaped mounting bracket 80 whichserves as a base for the complete unit.

The switches are operated by means of a switch operator 81 carried by ashaft 82 which extends between the base member 71 and the bracket 80. Itwill be apparent that rotation of the shaft and switch operator 81 in aclockwise direction as seen in FIG. 8 opens the switches against thebias of the switch blades. Conversely rotation of the switch operator ina counterclockwise direction as seen in FIG. 8 permits the switches toclose.

Preferably the shaft 82 carries tubular insulators 83 in front of and inback of the switch operator 81. It also carries a barrier 85 ofinsulating material for preventing arcing from the contacts to theoperating mechanism to be described.

The shaft 82 at its rear end carries a lever 86. The lever 86 and theswitch operator 81 are keyed to the shaft 82 in a suitable manner sothat the lever and switch operator are maintained in a fixed angularrelationship with each other. The lever 86 also carries a forwardlyextending stud 87 which in turn carries a roller 88. This roller isengaged by the cam surface 89 of a lever 90 attached to a bearing 91which is carried by a stud 92 attached to the base bracket 80. A torsionspring 94 fits over the bearing 91. One end of the spring 94 engages astud 95 attached to the lever 90. The other end of the torsion springbears against a stud 96 attached to the base bracket 80. It will beapparent that the torsion spring serves to bias the lever 90 in acounterclockwise directron as seen in FIG. 8.

The lever 90 is actuated by means of a solenoid generally indicated as100. This solenoid 100 is of well known construction and is attached tothe upper port1on of the U-shaped base bracket 80. This solenoidincludes a plunger 101 carrying a pin 102 which fits into a slot 103formed in the lever 90.

Also pivotally mounted on the stud 92 is an antibounce member 105. Thismember is of hook-like configuration and includes a pin 106 whichextends into a slot 107 formed in lever 90. This anti-bounce member 105is biased relative to lever 90 by a torsion spring 108. As shown in FIG.8 this spring biases member 105 in a clockwise direction causing the pin106 to bear against the left side of the slot 107 in the lever 90.

The lower end of the lever 86 is formed with gear teeth 110 which meshwith teeth of the pinion 111. This pinion 111 is attached to a flywheel112 and is carried on The parts are shown in the positions assumed whenthe solenoid 100 is de-energized. At this time the spring 94 has rotatedthe lever 94) to its counterclockwise limit of rotation in which thelower surface of the lever 115 strikes the shaft 82. At this time thecam surface 89 has born against the roller 88 and moved the lever 86 toits clockwise limit of rotation. As the lever 86 and the switch operator81 are in fixed relationship on the shaft the switch operator is in aposition which pushes the spring switch blade 72 to the left for openingthe contacts. The upper switch is open in the same manner.

When the solenoid is energized its plunger 101 is pulled upwardly whichrotates the lever 90 in a clockwise direction about its pivot 92. Thisraises the cam surface 39 from disengagement with the lever 88. Theassembly including shaft 82 switch operator 31 and roller 86 are nowfree to rotate in a counterclockwise direction under the bias of theswitch blade 72 and also the upper switch blade. The switches thus moveto closed position. This movement however requires rotation of theflywheel 112 which serves to control the speed at which the switchesclose and thus avoids bouncing of the contacts.

When lever 94) was pulled in a clockwise direction by inward movement ofthe solenoid plunger 101 it also permitted the hook-like anti-bouncemember 1115 to approach the roller 38 on lever 86. The action of themovement of lever 90 is instantaneous byv the solenoid. However,movement of the lever 86 and roller 88 is delayed by the flywheel 112.When the roller 88 catches up with the cam surface 89 of the lever 90 atthe end of the stroke it tends to bounce. However, at this time theanti-bounce member 105 has come under the roller 88- which prevents thisaction When the solenoid is de-energized a spring 94 is free to rotatethe lever 90 in a counterclockwise direction. At this time the camsurface 89 engages roller 88 and I0- tates lever 86 in a clockwisedirection, thus rotating the switch operator in a manner to move theswitch to open position against the spring bias affect of the springswitch blade 72.

The cam surface 89 of lever 90 is plotted to reverse the spring rate ofthe spring 94. In other words, when the lever 90 rotatescounter-clockwise the angular clockwise travel of lever 86 progressivelydecreases. By properly plotting the curve of cam 89 the spring 94 isgiven a negative spring rate which balances the spring rate of theswitch blade 72.

As in the case of the embodiment of the invention shown in FIGS. 1, 2and 6, the switch operator 81 moves beyond the point required forclosing the contacts when the solenoid 100 is energized. In other words,the contacts first close and the switch operator continues rotatingcounterclockwise to a predetermined overtravel position. Thus, when thesolenoid is de-energized the initial movement of the switch operator inthe clockwise direction first takes up the overtravel. At this time theflywheel 112 slows down the movement of the switch operator. Theflywheel also stores energy which is available for opening the contactswhen the switch operator 81 engages the switch blades. Thus thisarrangement provides for a slow, controlled breaking action of thecontacts coupled with storing of energy for breaking the contacts openin the event they should weld.

From the foregoing description it will be aparent that both embodimentsof the invention provide a maximum operating force for the switches witha minimum of energy required. Also, the combination of the negativespring rate mechanism with the flywheel eiiect serves to providecontrolled making and breaking speeds of the switches. This eliminatescontact bounce on the make action and minimizes arcing on the break.

While a preferred form of the invention has been shown and described, itwill be apparent that many modifications may be made without departingfrom the spirit and scope of the invention. It is, therefore, desired tobe limited only by the scope of the appended claims.

I claim:

1. In a switching mechanism, a pair of cooperating contacts, a movablemember for moving one of said contacts, said movable member being biasedin one direction, operating means for moving said movable member againstits bias, said operating means including a spring and motiontransmitting means for transmitting motion of the spring to the movablemember, said motion transmitting means being constructed and arranged toreduce progressively the amount of motion transmitted as the springbecomes unstressed.

2. In a switching mechanism, a pair of cooperating contacts, a movablemember for moving one of said contacts, said movable member being biasedin one direction, operating means for moving said movable member againstits bias, said operating means including a spring and motiontransmitting means for transmitting motion of the spring to the movablemember, said motion transmitting means being constructed and arranged toreduce progressively the amount of motion transmitted as the springbecomes unstressed, a flywheel, and means for translating motion of theoperating means into rotary motion of the flywheel for controlling themake and break speeds of the moving contact.

3. In a switching mechanism, a pair of cooperating contacts, movablemeans :for moving one of said contacts, said movable means being 'biasedin one direction, operating means for moving said movable means againstits bias, said operating means including a spring and motiontransmitting means for transmitting motion of the spring to the movablemeans, said motion transmitting means including a cam operated by thespring and a cam follower riding said cam for moving the movable means,said cam being proportioned with progressively decreasing throw whenmoving in the direction in which the spring is becoming unstressed.

4. In a switching mechanism, a pair of cooperating con tacts, movablemeans for moving one of said contacts, said movable means being biasedin one direction, operating means for moving said movable means againstits bias, said operating means including a spring and motiontransmitting means for transmitting motion of the spring to the movablemeans, said motion transmitting means including a cam operated by thespring and a cam follower riding the cam :for moving the movable member,a fly cont-acts, movable means for moving one of said contacts, saidmovable means being biased in one direction,

operating means for moving said movable means against its bias, saidoperating means including a spring and motion transmitting means fortransmitting motion of the spring to the movable means, said motiontransmitting means including a cam operated by the spring and a camfollower riding said cam for moving the movable means, said cam beingproportioned with progressively decreasing throw when moving in thedirection in which the spring is becoming unstressed, a flywheel, andmeans for translating motion of the cam into rotary motion of theflywheel for controlling the speed of said cam.

6. In a switching mechanism, a pair of cooperating contacts, movablemeans for moving one of said contacts, said movable means being biasedin one direction, operating means for moving said movable means againstits bias, said operating means including a spring and motiontransmitting means for transmitting motion of the spring to the movablemeans, said motion transmitting means comprising a cam mounted 'forrotation by said spring and a cam follower riding said cam for movingthe movable means, said cam being proportioned with progressivelydecreasing throw when moving in the direction in which the springbecomes unstressed, a flywheel, a pinion for rotating said flywheel,said cam having a portion formed with gear teeth meshing with saidpinion, whereby movement of the cam is controlled by said flywheel.

7. In a switch, a pair of cooperating contacts, a switch operator formoving one of said contacts for opening and closing the switch, saidswitch operator being arranged with more travel than required to operatethe switch so that on movement in one direction it moves the switch toone of its positions and then overtravels to a predetermined position,means including a spring for biasing the switch opeartor in the oppositedirection, a flywheel arranged to rotate with movement, of the switchoperator, said flywheel retarding the speed of the switch operator andstoring kinetic energy during return movement of the switch operatorthrough its overtravel to provide force for operating the switch.

8. In a switch mechanism, a movably mounted switch operator, a firstspring, motion transmitting means between the first spring and theswitch operator for biasing the switch operator in one direction, asecond spring op posing the first spring for biasing the switch operatorin the opposite direction, said second spring having greater force thanthe first spring so that when released it moves the switch operator inits direction and applies tension to the first spring, control means forfirst releasing the second spring to eflect movement of the switchoperator in one direction and then releasing the switch operator fromthe second spring so the first spring moves the switch operator in theopposite direction, said motion transmitting means between the firstspring and said switch operator being constructed and arranged todecrease progressively the amount of motion transmitted from the switchoperator to the first spring when the switch operator is moved by thesecond spring 9. In a switch mechanism, a movably mounted switchoperator, a first spring, motion transmitting means between the firstspring and the switch operator by biasing the switch operator in onedirection, a second spring opposing the first spring for biasing theswitching operator in the opposite direction, said second spring havinggreater force than the first spring so that when released it moves theswitch operator in its direction and applies tension to the firstspring, control means for first releasing the second spring to eflectmovement of the switch operator in one direction and then releasing theswitch operator from the second spring so the first spring moves theswitch operator in the opposite direction, said motion transmittingmeans between the first spring and said switch operator beingconstructed and arranged to decrease progressively the amount of motiontransmitted from the switch operator to the first spring when the switchoperator is moved by the second spring, a flywheel, and means fortranslating motion of the switch operator into rotary motion of theflywheel for controlling the speed of said switch operator.

10. In a switching mechanism, a pair of cooperating contacts, movablemeans for moving one of said contacts, said movable means being biasedin one direction, operating means having a spring which when releasedovercomes the bias of said movable member for moving the same in theopposite direction, said operating means including motion transmittingmeans between the spring and movable means constructed and arranged toreduce progressively the amount of motion transmitted as the springbecomes unstressed, and an electro-magnet for selectively holding orreleasing said spring.

11. In a switching mechanism, a pair of cooperating contacts, movablemeans for moving one of said contacts, said movable means being biasedin one direction, operating means having a spring which when releasedovercomes the bias of said movable member for moving the same in theopposite direction, said operating means including motion transmittingmeans between the spring and movable means constructed and arranged toreduce progressively the amount of motion transmitted as the springbecomes unstressed, a flywheel, means for translating motion of theoperating means into rotary motion of the flywheel for controlling themake and break speeds of the moving contact, and an electro-magnet forselectively holding or releasing said spring.

12. In a switching mechanism, a stationary contact, a flexible leafspring type switch blade having one end fixed and one end movable, amovable contact carried by said switch blade cooperating with saidstationary contact, said switch blade being biased in one direction,operating means for moving said switch blade against its bias, saidoperating means including a spring and motion transmitting means fortransmitting motion of said spring to said switch blade, said motiontransmitting means being constructed and arranged to reduceprogressively the amount of motion transmitted as the spring becomesunstressed.

13. In a switching mechanism, a stationary contact, a flexible leafspring type switch blade having one end fixed and one end movable, amovable contact carried by said switch blade coop-erating with saidstationary contact, said switch blade being biased in one direction,operating means for moving said switch blade against its bias, saidoperating means including a spring and motion transmitting means fortransmitting motion of said spring to said switch blade, said motiontransmitting means including a camming surface arranged to reduceprogressively the amount of motion transmitted as the spring becomesunstressed.

14. In a switching mechanism, a stationary contact, a flexible leafspring type switch blade having one end fixed and one end movable, amovable contact carried by said switch blade cooperating with saidstationary contact, said switch blade being biased in one direction,operating means for moving said switch blade against its bias, saidoperating means including a spring and motion transmitting means fortransmitting motion of said spring to said switch blade, said motiontransmitting means including a cam operated by the spring and a camfollower riding the cam for moving said switch blade, said cam beingporportioned with progressively decreasing throw when moving in thedirection in which the spring is becoming unstressed.

References Cited by the Examiner UNITED STATES PATENTS 2,762,884 9/1956Van Eyk 200-l17 BERNARD A. GILHEANY, Primary Examiner.

R. N. ENVALL, JR., Assistant Examiner.

1. IN A SWITCHING MECHANISM, A PAIR OF COOPERATING CONTACTS, A MOVABLEMEMBER FOR MOVING ONE OF SAID CONTACTS, SAID MOVABLE MEMBER BEING BIASEDIN ONE DIRECTION, OPERATING MEANS FOR MOVING SAID MOVABLE MEMBER AGAINSTITS BIAS, SAID OPERATING MEANS INCLUDING A SPRING AND MOTIONTRANSMITTING MEANS FOR TRANSMITTING MOTION OF THE SPRING TO THE MOVABLEMEMBER, SAID MOTION TRANSMITTING MEANS BEING CONSTRUCTED AND ARRANGED TOREDUCE PROGRESSIVELY THE AMOUNT OF MOTION TRANSMITTED AS THE SPRINGBECOMES UNSTRESSED.